C shell: kill process syntax

Question

I'm trying to write my own C shell. I'm wondering how to make calling 'kill' in the command line work. For example,

shell> kill 2      
shell: process 2 has been killed

Line 1 is user input 'kill 2'

Line 2 is program-printed message of what has been done.

I know I have to take the pid as the argument I believe and send the SIGKILL signal. Using something like

 kill(pid, SIGKILL);

How do I connect this kill function to respond when a user inputs 'kill 2' in a C implementation? I guess I'm having a hard time connecting it to the command line arguments for implementation. I might need strtok/atoi? Thank you.

Nandan Bharadwaj · Answer 1 · 2014-02-18T06:44:13.300

1

Better you go for "getopt" which might look as fallows,

#include <stdio.h>
#include <ctype.h>
#include <sys/types.h>
#include <signal.h>

int pid;
if((pid = getopt(argc, argv, "0123456789")) != -1)
    if(isdigit(pid)){
        if(kill(pid, SIGKILL) == -1){
            perror("KILL:");
            exit(0);
        }
    }else{
        printf("Input format: kill <pid>");
    }

edited Feb 18 '14 at 06:44

answered Feb 18 '14 at 06:13

Nandan Bharadwaj

530
3
7

What does the "0123456789" part inside strtok refer to? Is it the process #? – user3295674 Feb 18 '14 at 06:23
sorry for the previous logic, and yes "0123456789" refers to pid of the process. – Nandan Bharadwaj Feb 18 '14 at 06:36

Jayesh Bhoi · Accepted Answer · 2014-02-18T06:35:14.067

0

#include<stdio.h>
#include<sys/types.h>
#include<signal.h>

int main(int argc, char **argv)
{
    if (argc < 3)
    {
        printf("usage: ./kill OPERATION(kill/cont) PID\n");
        return -1;
    }

    if(strcmp(argv[1],"kill") == 0 )
    {
        printf("Kill:\n");
        kill(atoi(argv[2]), SIGKILL);
    }
    else  if(strcmp(argv[1],"cont") == 0)
    {
        printf("cont:\n");
        kill(atoi(argv[2]), SIGCONT);
    }
    else
    {
        printf("Kill default:\n");
        kill(atoi(argv[2]), SIGKILL);
    }

    return 0;
}

edited Feb 18 '14 at 06:35

answered Feb 18 '14 at 05:59

Jayesh Bhoi

24,694
15
58
73

Thank you. What happens if I try to implement another call, such as 'cont', as kill(pid, SIGCONT)? In the first 'if' statement can I do something like if (argv[1] == kill)? How can I make sure it goes to the right one? – user3295674 Feb 18 '14 at 06:13
So you need to pass extra field as command line for what you want means need to continue or just kill it.have updated my post soon. – Jayesh Bhoi Feb 18 '14 at 06:25

C shell: kill process syntax

2 Answers2